北祁连浪力克地区毛藏花岗闪长岩年代学、Hf同位素及地球化学特征

发布时间：2018-05-29 08:53

本文选题：地球化学 + 中钾钙碱性侵入岩　；参考：《矿床地质》2017年01期

【摘要】：青海省门源县浪力克地区毛藏花岗闪长岩岩体位于北祁连冷龙岭东段,文章通过开展年代学和岩石地球化学研究,对该岩体的形成时代进行厘定并探讨其成因。LA-ICP-MS锆石U-Pb测年结果表明,毛藏花岗闪长岩体形成时代为(471.9±8.6)Ma(MSWD=1.6),属早古生代奥陶纪;锆石Hf同位素分析结果显示,该类岩石εHf(t)值介于-13.3~5.26,T_(DM2)为1112.4~2284.7 Ma,暗示岩浆可能是由壳幔混合作用形成,其壳源源区很可能是古元古代及中元古代古老地壳岩石。此外,岩石地球化学研究结果表明,该类岩石属弱过铝质中钾钙碱性系列的I型花岗岩,明显富集大离子亲石元素(如K、Ba、Rb)和活泼不相容元素(如Th、U),相对亏损高场强元素(如Nb、Ta、Ti、P),形成于俯冲消减环境,为火山弧花岗岩。
[Abstract]:The Maozang granodiorite body in Langlik area, Mengyuan County, Qinghai Province, is located in the eastern section of the Lenglongling Mountains, North Qilian. The study on geochronology and geochemistry is carried out in this paper. The age of formation of the body was determined and its origin was discussed. The results of zircon U-Pb dating of LA-ICP-MS indicate that the age of formation of the Mao Zang granodiorite is 471.9 卤8.6 MaMSWD1.6, which belongs to the early Paleozoic Ordovician, and the zircon HF isotopic analysis shows that, The 蔚 Hft2 value of this kind of rock is between -13.3U 5.26T / M _ 2) = 1112.4 ~ 2284.7 Ma. it suggests that the magma may have been formed by the mixing of crust and mantle, and the origin of the crust is probably Paleoproterozoic and Mesoproterozoic crustal rocks. In addition, the results of petrogeochemical study indicate that this kind of rock belongs to the I-type granite of potassium calc-alkaline series in weakly peraluminous medium. The enrichment of large ion lithophile elements (such as Ko Baan Rb) and active incompatible elements (such as Thu U), relatively depleted high field strength elements (such as NbBU Taheng TiTiPU), formed in subduction environment and belong to volcanic arc granites.
【作者单位】：核工业西藏地质调查院;中国地质调查局西安地质调查中心;
【基金】：中国地质调查局“青海门源县银灿-浪力克1∶5万成矿预测”项目(编号:1212011221043)和“青海门源县宁缠河-牛头山一带铜多金属矿调查评价”项目(编号:12120115022401)资助
【分类号】：P597;P588.12

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